This invention relates to the use of laminar air flow slot venting for sails such as a headsail, mainsail or asymmetrical spinnaker used on most sailboats. The state of the art designs for the use of slot venting between two elements or sail sections are found on wing sails, such as the BMW Oracle racing USA-17 trimaran in Americas Cup 2010, where air flows from the windward side of the sail and aftward along the leeward side of the aft element or flap, which concept originated with slotted aircraft landing flaps. The C-Class catamaran is similar in design, although has an additional flap between the two element sections which helps direct windward air flow aftward closer and more parallel to the leeward side of the aft element, further energizing laminar air flow along the surface boundary layer. These designs allow for higher angles of attach with more camber generating higher lift and drag ratios which is desirable for stable high performance multihulled sailboats. Numerous US patents for hard wing sails utilize a slot to direct windward air flow aftward along the leeward side, as well as U.S. Pat. No. 5,732,643 of a “sail”. Although, in U.S. Pat. No. 5,732,643 the first element or “head sail” is wing shaped out to it's leach, and made of rigid or braced segments which pivot substantially about the mast, unlike a sail having a thin airfoil shape. U.S. Pat. Nos. 5,031,560, 5,123,368 3,776,170 and 2,971,488 for sails, all have open vents with apertures parallel to the sail's surface and direct air flow from the windward side to the leeward side of the sail substantially outward from the surface, and not directly aftward along the aft section of the sail as in the description for this invention.